@Philipwonel I grew chayote many years ago, and I only had one vine, which was self-fruitful. I just checked Wikipedia, which says, "The plant bears male flowers in clusters and solitary female flowers." I think one will do the trick, but give it plenty of room—in your climate, it will really turn into a monster. Like most plants in the gourd family, it will probably benefit from hand-pollination in the early part of the season.